Rotary dumper Working N scale rotary dumper http://www.melbntrak.com/photos/noelp/noel17.jpg Oh and the other end to complete the story. A working loader also. http://www.melbntrak.com/photos/noelp/noel02.jpg
I wonder if the solution is not to keep the proven and workable couplers already in hand and use a vacumn process to offload the coal loads? The thought being, as mentioned here, that the emptying is inside a building and out of view. You simply move the cars through the loadout as they move the vacumn sucks op the coal. A gentlemen in New richmond WI built a working coal unloader using standard coal inserts. He glued a nail to the bottom of the coal load, and put it in the car. At the power plant he models the offload building and inside the building is a belt on two pullies. On the belt are several round magnets, as the railcar moves under the belt the magnet moves over the car and pulls the load out of the car and carries it off to the side of the track. There the magnetic pull is broken by two poles mounted each side of the belt and the laod falls through a hole in the layout to an ice cream bucket that catches the loads for movement back to the mine area and manually placed back in the cars. The plant design is based on the Bayport MN coal plant and the unit train is broken up into smaller cuts of cars and moved through the dumper with a switch engine, the modeler does the same. I've seen it and it is a neat solution. Joe
These are the components for changing a rapido-style coupler to a rotary coupler. The coupler is modified: 1) the tee is cut down to something almost round. 2) The block is removed from the tee/shank intersection 3) the shank is rounded off to an octagon. Otherwise it binds on the slot when you rotate the car. The truck is modified - remove the rapido coupler and spring, cut about half the spring retaining sprue off. The coupler is inserted in the ABS box, then the box is inserted into the truck's coupler box slot down.
Flood loader in operation. This has been running flawlessly for years. It loads about 4 cars a minute. The loader is powered by an unmodified tortoise, mounted sideways to push a threaded rod up and down. The rod operates two "valves" that turn the flow of coal on and off. In the up position the upper valve opens, allowing coal to drop to a measuring bin. The bin holds exactly the amount of coal needed to fill a car. The lower valve closes. In the down position the rod closes the top valve to the bin. The bottom opens, allowing the coal in the bin to drop into the car. In operation a dpdt toggle switch operates the tortoise. Ideally, as the train moves slowly forward under the chute the toggle dumps the coal, then between cars it toggles to fill the bin. In practice it is very hard to run the train slow enough to allow enough time for the bin to refill between cars, so I have to stop the train between cars. At speeds this slow I have to do a lot of track and locomotive wheel cleaning. I am considering a double bin, where one fills while the other is dumping, to avoid having to stop the train. The key innovation was the valve desgin. You cannot have any tight-fitting surfaces when you deal with coal - they jam. These basically place a flat surface under the chute. As the coal piles up on the surface it forms a cone. When the cone gets high enough to hit the bottom of the chute, flow stops. To start the flow, the cylinder rotates so that a hole is under the chute.
Dumper pics. My inspiration was a video showing a Detroit Edison coal train unloading at a plant in Monroe. The operator drives the locomotive into the building then gets out and goes to lunch. The dumper takes over. An arm comes down and pushes the train forward one car at a time. Each car is turned upside down and dumped. This requires the rotary couplers! In operation the one on my layout works the same way, except that you have to uncouple the engine and drive it out of the way first. Operation is by a power switch. The push arm and dumper work automatically until you shut the power off. Unlike the loader, this requires occasional adjustment of the micro switches that control the whole thing. Power is provided by two modified tortoises that wind and unwind fishing line. Radio Shack micro switches control the tortoises via AC and diodes. So far I only have three rotary couplers. Here the engine pulls into the dumper. Please imagine a building covering all of this up. The pusharm is in the "up" position. The engine is uncoupled. When the power is cycled on, the pusharm goes back, drops, and reversed direction. It pushes the car (and the whole train) forward. When the pusharm hits a limit switch, it stops and the dumper rotates. Springarms hold the car to the track. As they rise up during rotation, they pull up a fishing weight which bends them down to hold the car. As the dumper turns a pin eventually catches the push arm and swings it up. Full up on the push arm toggles a micro switch that controls the direction of the push arm and sends it back over the next car. A limit switch stops the forward rotation of the dumper. Another switch, hit by the push arm's traveler, reverses the dumper. Finally we are back to the part of the cycle where we started. The push arm continues back until it falls off the top rail, drops behind the next car, and toggles the switch that sends it forward again.
jpf94, I did something similar to the vacuum idea, but its the opposite. The "old" mine (versus "new" flood loader) is a lightly modified New River Mining. Coal is loaded into cars by air. I use a fish tank air pump (a fairly powerful one) to basically blow coal from a silo into a small bin over the car being loaded. Operation is by a foot pedal salvaged from a sewing machine. The coal moves thru fish tank airline tubing. It is a real pita to load this way because you have to move the car under the chute and it can easily overflow. On the other hand, you get to use the kickback dumper to unload and thats a lot of fun. We won't talk about the coal dust though.
Just found this old thread - dumper in action here: The dumper is one generation after the one shown above. The solve the problem of coupler friction by holding down the cars on either side so that they can't rotate; that made made the whole thing reliable. I sort of gave up on the rotary couplers - I think I have 5 that don't derail when running empty trains. The rest of the cars are connected by small rubber bands from my granddaughter's braces - ugly but reliable.
I just read through this thread because I was curious as to how one would model this in N-scale. As I read it, I had a thought. Could you use a small magnetic bead for the rotating coupler. Some of the newer magnets are fairly strong so just might be able to provide enough strength to hold a train together. The nature of the ball would mean that there is minimal surface area for friction and no "joint" that had to rotate as the surface of the ball should allow any rotation. With a strong enough magnet, the cars would be held together while the car rotates and allow continuous movement through the rotary unloader. I've seen 2mm magnetic beads with 1mm holes in them for sale on EBay. These may be small enough but not sure if they are strong enough. The hole could function as the coupler holding device for the bead. So, for those of you who are involved in this, is this idea totally nuts or does it have some merit? Rob Hampton, New Brunswick
Can you clarify: The magnet ball is the coupler, and the other car has a steel plate instead of a coupler? Or the magnet is mounted on the coupler shank and holds it against a plate in the coupler box? Might work... I've got some cylindrical mags for magnetic uncoupling that seem like they would be powerful enough. As an added bonus it would add realism, allowing you to "break a coupler" if you rough-handle the train. Tough part is anything slightly off square pulls to the side causing derails. Worth fiddling with. BTW afaik I'm the only bozo on this rotary coupler bus.
A friend of mine has a N scale mining layout and he uses fishing swivels which fit into the micro trains coupler box he has been using them for years through his scratchbuilt rotary dumper. best regards Vic Fitzpatrick vicsmodels
In the same vein...I alway wondered if Bead Chain would work. I suppose most anything used would mean permanently couple cars.
Fishing swivels work, although backing up can get a little iffy. Some day when the rubber bands go brittle I'll probably replace them with the swivels. I'd be very interested in pics of your friend's operation.
If you remove the existing coupler from its pocket and just glue a magnetic bead to the opening you should have a functioning magnetic coupler that can swivel and rotate regardless of the car's orientation. Since the bead, or ball, has no flat surface, there is nothing to bind or catch as the car rotates and precision isn't required. As long as the magnetic field is strong enough, it should remain coupled to the next car. The Neodymium type magnets appear to have strength but I don't know if they would work in such a small size. Still, a couple of dollars for a bunch of 2mm beads wouldn't break the bank if you want to experiment. It would seem to me to be simple enough, but then again, maybe not. Rob Hampton, New Brunswick
OK, got it. Both sides have to have a magnet, so there will be at least two polarity issues to deal with. Some precision is required though as any off-center pull can pick the points. I've found 3mm but not 2mm on Amazon.
Hi NtheBasement, I for got to mention he has a loader as well where the whole train rolls through and loads car by car then travels around the layout to the port where his rotary dumper is situated complete with a modern ore carrier. He scratchbuilt his dumper out of brass with clock gears and and precision motor. You mention about being a bit iffy backing up ? I dont think he had any issues and he has used them for over 20 years. His layout is loosely based on the Iron Ore railroads of the Pilbra in rugged Western Australia, Mt Newman, Hammersley Iron, BHP and Rio Tinto. If you google it you will see how big the operations and railroads are. Best regards Vic Fitzpatrick
Hi Nthe Basement I have some pics but it comes up with an error times out before they download. I can send my email add. ispoke with the owner of the layout for permission to send or post any pics. He has video of the layout and operation if interested. best regards Vic Fitzpatrick vicsmodels
Update time. The old rubber band couplers that have been reliable for 5 years. Starting with mtl trucks, remove the couplers and spring, drill a hole for a pin to retain the rubber band. The rubber bands are 3/8", used for orthodonture. I've just today replaced one of the rubber bands with a #2 (not 2/0) fishing swivel. It seems to work but hasn't yet stood the test of time. Some options that I haven't tried: drill the pin holes farther in to get closer coupling, or use a larger swivel and lasso the coupler's built in pole instead of using pins. Note those are drawbars, not couplers, which makes railing a train a real challenge. Left to right a true working rotary, swivel, and rubber band, all under normal tension. Kudos to @vicsmodels for getting me rolling on the swivels. I got these 3mm beads and they certainly seem strong enough; a single bead lifts a 2.15 ounce fork but won't lift a 2.6 tablespoon. I assume magnet-to-magnet will be > 4 ounces. https://www.amazon.com/gp/product/B07FC7XH14/ref=ppx_yo_dt_b_asin_title_o00__o00_s00?ie=UTF8&psc=1 Trying to figure out how I'll glue them in with the proper north/south poles on each end. Each car will need a north truck and a south truck, right? At least the whole train won't be one big long drawbar if I do this.
A whacky side effect is that the ortho rubber bands look somewhat transparent making it look like the cars are not coupled but are following each other through "magic".
